High barium-content phenolic compounds



United States Patent HIGH BARIUM-CON TENT PHENOLIC COMPOUNDS James E. J. Kane, Elizabeth, N. J., and John R. Jones,

Seattle, Wash, assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application October 1, 1952, SerialNo. 312,643

9 Claims. 01. 260-609) The present invention relates to barium salts of a phenolic material having a high ratio of metal to phenol content, and to an improved process for making same.

It is frequently desired to prepare barium salts of various types of phenols such as 'alkyl phenols, alkyl phenol sulfides, amino phenols, acyl aminophenols and the like. Such compounds have a variety of uses and are particularly valuable as detergent and antioxidant additives for lubricating oils and the like. It is also frequently desirable to incorporate a relatively large amount of metal into the phenolic compound in order to improve the detergency characteristics of the same or to obtain other desired properties. It has been extremely difficult to obtain high ratios of metal to phenol in prior art procedures. It is the primary purpose of the present invention to provide :a simple and inexpensive expedient for obtaining unexpectedly high barium-content salts of such phenolic materials.

In accordance with the present invention, the phenolic material to be converted to the barium salt is treated with a basic-reacting barium compound in an amount in excess of that required for neutralization in the presence of carbon dioxide whereby a high barium-content metal salt is formed. It has been found that unexpectedly high conversions of hydroxyl groups to metal phenate radicals takes place in the presence of a substantial excess of the basic barium compound by this process, particularly when both carbon dioxide and steam are employed. The conversion of hydroxyl radicals is considerably greater than is obtained under the same conditions when no carbon dioxide is employed.

It is known in the art to treat metal salts of alkyl phenols, alkyl phenol sulfides and the like with weakly acidic acids such as carbon dioxide in the presence of steam. Such treatment, however, is carried out on the metal salt rather than on the material undergoing neutralization in order to improve the water sensitivity Olf themetal salt. The metal salt is subject to hydrolysis by treatment with carbon dioxide and steam, and the hydrolytic action lowers the total metal content of the material unless the amount of treating agents are carefully controlled. The present process is to bedi'stinguished from such prior art methods, since its essential feature lies in conducting the neutralization in thepresence of carbon dioxide whereby the unexpected improvements are obtained.

The reasons for obtaining an abnormally high barium content in the metal'salts produced by the present process are obscure and cannot be' explained at the wpresent time. It has been found that, while basic barium neutralizing agents may be effectively used, other metal neutralization agents will not respond to form high-metal salts. by this process. For example, whereas barium hydroxide will readily produce such materials, lime, when used in sim ilar molar concentrations, does not go much beyond the point of conventional neutralization.

. 70 It is not desired to be-bound by any theory orhypoth esis as to the mechanism-of the reaction, but it has been 2,. found that the carbon dioxide is chemically combined with the resulting salt. Phenolic compounds are normally neutralized by barium hydroxide by reacting an equiv alent of two mols of hydroxyl radical per mol of barium, presumably to form the following structure:

FORMULA I tit) When using equal molar concentrations of hydroxyl radical and barium hydroxide, substantial, proportions of the following compound may be formed:

FORMULA II o BaOH When using concentrations equivalent to above two mols of barium hydroxide per mol of phenol, in accordance with prior art processes, it appears that the resulting compound may have a structure as follows:

FORMULA III 0 Ba 0 H Compounds such as those of Formula III are difiicult to form, however, by conventional processes, and are usulaL ly ttormed in fairly low yields with poor utilization of neutralization agent.

The exact composition of barium salts prepared by the present process is not known. However, the resulting compounds apparently have a different structure to prior art compounds as evidenced by the fact that the present compounds release substantial amounts of carbon dioxide whenhydrolyzed with a strong inorganic acid. It is believed that carbon dioxide enters the product as a barium carbonate to form a compound having the possible structure FORMULA IV may, be formed:

FORMULA V o oBa0 i'i-OBaOHO-Ba-O H in which Rrepresentsalkyl groups, each having in the range of 4 to 20 carbon atoms and x is an integer such as from one to five. This structure could apparently split out one mol of water to form:

H O l n' s.- r.

containing molar ratios of barium to phenol hydroxyl of 1.5:l.0 and of carbon dioxide to hydroxyl of 0.5110. It is likely that the reaction produces a mixture of compounds of varying structure, but the present invention contemplates such mixtures. Regardless of the structures of the compounds, the formation of the barium phenates takes place readily and smoothly giving an eflicient utilization of barium neutralization agent. The resulting compounds are stable and effective for use per so as lubricant additives and the like and for use as intermediates in making various derivatives.

The phenolic materials used for preparing the barium salts are those containing one or more phenolic oxygen atoms may be illustrated by the formula ArOX wherein Ar is an aromatic ring, as described below and X is hydrogen or a metal other than barium. X is preferably hydrogen, and one or more -OX groups may be attached to the Ar group. Ar represents a carboxylic aromatic ring or heterocyclic aromatic ring, such as a ring containing sulfur, oxygen or other atom. The Ar ring may contain other substituent groups such as hydrocarbon groups including alkyl radicals, cycloaliphatic radicals, alkaryl radicals and the like. The ring may also include substituents such as amino groups, alkoxy groups, acyl groups, sulfur atoms, sulfonic groups, and the like. Condensation products of phenolic compounds with aldehydes, ketones and the like, such as formaldehyde and acetone, may also be used.

Alkylphenols are particularly useful and these include cresols, xylenols, thymol, orcinol, decylphenols, wax phenols, petroleum phenols and the like. The so-called bis phenols in which two hydroxy aromatic rings are connected by an alkyl radical, are also applicable to the present process. These include diphenylolpropane, 2,2-bis- (2-hydroxy-3-tert.-butyl-5-methyl-phenyl)-propane, and the like. Aminophenols include diethyl aminophenols, benzyl aminophenols, and acylaminophenols such as N-propanol-p-aminophenol. Acyl phenols such as acetyl phenol,'where an acyl group is attached directly to the ring, the like may be used. Particularly useful are the alkylphenol sulfides such as tert.-amylphenol sulfide, ten..- octyl phenol sulfide and other compounds of this class which are well known to'the art. Any such substituent groups should not block the activity of the phenol hydroxyl group for forming the barium salt.

This invention also has application to preparing barium salts of phenates containing a metal other than barium. For example, the phenolic compound may be partially or completely neutralized to form a calcium, magnesium, tin, zinc or other salt, and then the salt is treated as described above to form a mixed metal salt containing a high barium content. 1

It should be obvious to the skilled workman that the above constitutes only a partial list of the phenolic compounds useful in accordance with the present invention. The essential feature of the present invention lies in the neutralization of materials containing at least one phenolic oxygen atom, notwithstanding the other types of substituent groups that may be attached to the aromatic ring. For this reason, the term phenolic compound will refer to the variousclasses of phenols and substituted phenols and their metal phenate derivatives that are susceptible to reaction with basic barium compounds.

Basic reacting barium compounds useful in the present invention include barium oxide, barium hydroxide, barium hydroxide pentahydrate, barium hydroxide octahydrate and the like. These compounds are well known to the art for use in producing barium phenates. The amount of basic reacting barium compound used in the reaction will be such that the ratio of barium to phenolic hydroxyl radical or phenate radical, on a molar basis, is at least 1.3:].0 and preferably is above 1.5 :1.0. Thus, compounds having a Ba/ OH mol ratio of above 1.0210 and preferably above l.2:1.0 are readily formed. The amount of barium compound used will depend on the desired barium content of the metal salt, the amount of metal going into the complex salt being almost proportional to the ratio of barium to hydroxyl radical provided sufficient carbon dioxide is used. Thus, for extremely high metal-content salts, the mol ratio of barium to hydroxyl or phenate radical may be as high as 5:1 or even higher.

The neutralization reaction is generally carried out at a temperature in the range of about 50 to 200 C., but preferably is maintained above C. in order to obtain a relatively rapid reaction. The mixture is preferably stirred during neutralization. The reacting mixture is treated with gaseous carbon dioxide, preferably in the presence of water or steam, this operation being conducted for a suflicient length of time to incorporate the desired amount of metal and carbon dioxide into the phenolic compound. In a preferred embodiment of the invention, the reacting mixture is first blown with steam following which it is blown with carbon dioxide gas containing water vapor.

Several procedures may be used to obtain the desired results. For example, the barium compound in finely divided form is slowly added to the phenol in a suitable stirred reaction vessel while the gaseous materials are blown upwardly through the stirred contents during the neutralization step at atmospheric or higher pressures. It is generally desired to continue the blowing operation with the gases for a substantial period of time after addition of the neutralizing agent has been completed. This will insure the formation of the high barium content salt in stable form and will provide for maximum utilization of neutralization agent. Obviously, the neutralization step may be carried out by batch operation or continuously, depending on the type of equipment employed for the neutralization. In a batch operation, tl1e phenolic compound is placed in a suitable open or closed tank provided with heating coils and a pipe or other suitable distributing means for passing the carbon dioxide and steam into the reaction zone. A mechanical agitator may be provided. In continuous operations, the phenolic compound and barium compound may be charged into the top of a vertical tower which may contain. packing materials, such as Raschig rings and the like, and the carbon dioxide may be passed upwardly through the downfiowing reactants continuously. Contact times are readily controlled by charge rates and by adjusting the size of the treating zone. Such treating equipment is well known to the art and forms no part of the present invention.

The amount of carbon dioxide employed during neutralization should generally be sufiicient to incorporate at'least about 0.2 mol CO2 per mol of phenol hydroxyl radical into the finished product, preferably above 0.4 mol COz/mol OX. Since the amount of barium in the product is relatedto the CO2 entering into the reaction, COz/OX molar ratiosin the product of as high as 1:1 orhigher willv be desirable where extremely high barium contents are needed. The amount of CO2 used may be only slightly in excess of the amount to be incorporated in the salt providing eificient contact is achieved, such as n a well-stirred reactor operating under pressure for prolonged contact times. If the gaseous C0 2 is merely bubbled through the reacting mixture, it is not utilized effectively, and treatments well in excess of 0.5 to 1.0 mol C0z per mol OX radical will be needed. Under such conditions, CO2 treating times of above minutes, such as in the range of 1-6 hours, may be needed.

The amount of water used in the treatment does not appear to be critical but it should, be present for successful operation. It is possible that the carbon dioxide reacts most readily. as carbonic acid. This makes the presence ofwater highly desirable. Water should generally be present in an amountat least equivalent, on a molar basis, to the CO2 employed. It may be present to some extent as an impurity infthe solution undergoing reaction, particularly at low temperatures. At high temperatures, it may be introduced as steam or as a vapor in mixture with C02. A particularly desirable mode, when operating at high temperatures, is to treat the reacting mixture with steam for 15 minutes to 3 hours or so and then to treat with CO as heretofore described, the CO2 containing water vapor if desired.

After the treating operation iscompleted, the product may be filtered to remove solids such as unreacted neutralizing agent, bariumcarbonate or other materials.

Since the barium salts of phenolic compounds are generally viscous, the neutralization is preferably carried out in the presence of an inert solvent in which the phenolic compound and the barium salt thereof are soluble. Such materials include hydrocarbons, particularly the more parafiinic types, halogenated hydrocarbons and the like. Inert solvents such aspetroleum ether, naphthafractions, gas oil fractions and lubricating distillates derived from petroleum may be used depending on the molecular weight and solubility characteristics of the phenolic compound and its barium salts. The use of an inert solvent not only lowers the viscosity of the resulting solution but alsoaids in permitting good contact between the reacting materials. The reaction is also aided by carrying it out in the presence of an anti-foaming agent such as a high molecular weight alcohol, particularly when the reaction is conducted in the presence of an oil solution. Such alcohols include the so-called Lorol B alcohols derived from coconut oil, stearyl alcohol and the like. The use of these solvents and alcohols is well known in the art.

The resulting barium salt may be left as a concentrate in the inert solvent for subsequent storage, shipment and use. For example, the concentrate may contain 40% of the salt in a lubricating oil base. This concentrate may then be added to a lubricant in the desired concentration for improving various properties thereof. The solvent may be removed fromthe barium salt if desired. For example, a volatile solvent may be stripped from the salt by heating.

The barium salts are quite useful as additives for mineral oils. For example, in concentrations ranging from about 0.5 to they are effective for improving the detergency characteristics of lubricants. They are also useful in lower concentrations, such as down to 0.01% by weight, as stabilizers and inhibitors for motor fuels, diesel fuels, heating oils, greases, hydraulic fluids, etc. It may be used in combination with other additives, such as antioxidants, viscosity index improvers, pour point depressors, rust inhibitors, auxiliary detergents such as sulfonates, etc.

The barium salts obtained by this procedure may be used as intermediates in preparing other compounds. For example, they may be treated with elemental sulfur, sulfides of phosphorus and the like by well known prior art procedures to produce highly effective antioxidants, detergent and corrosion inhibitor additives and the like.

The practice of the present invention will be illustrated in connection with the following examples. It is to be understood, however, that these examples are not intended to restrict the invention in any way.

Example 1 A series of reactions were carried out in which tort.- octyl phenol sulfide was neutralized with barium hydroxide pentahydrate at about C. In each run, the phenol sulfide was blended with a lubricating oil to form a mixture containing about 36 weight percent octyl phenol sulfide, 60 weight percent mineral oil, and 4 weight percent C12C1a alcohols. Neutralizations were carried out with various amounts of barium hydroxide, the molar ratio of barium to phenol hydroxyl radicals being varied from 0.5 :1 to 1.75:1. All reactions were carried out in a reaction zone provided with a turbo mixer and with a steam jacket for heating purposes. In one series of runs, the barium hydroxide was added to the phenol-containing mixture, the material be ing stirred during the reaction and then subsequently filtered. In another series of runs, the materials during neutralization were blown with steam for a period of about one hour followed by blowing with gaseous CO2 saturated with water vapor for about two hours. The final products were filtered through a diatomaceous filter aid at a temperature of about C. The weight percent barium in the product and the hydroxyl conversion were then determined. The sulfur contents of the products ranged from 2.5 to 3.0% by weight. The hydroxyl conversion is based on the weight percent barium added per mol of hydroxyl radical. The results of these runs are shown in Table I below:

At a barium to hydroxyl molar ratio of below about 1.2:1, the use of carbon dioxide and steam had very little effect on the amount of barium added, whereas above about 1.3:].0, hydroxyl conversions were increased markedly and considerably larger amounts of barium were incorporated into the product. When steam and CO2 treating were omitted, little increase in OH conversion and barium content were realized by increasing the amount of barium hydroxide. The products prepared by this invention are substantially non-corrosive to silver and copper, and have low water sensitivity, good color and viscosity characteristics.

Example 2 A run was carried out in which tert.-octyl phenol sulfide was neutralized under conditions similar to those used in Example 1. The mol ratio of barium to hydroxyl radicals was 1.711, and the material was treated during neutralization with steam for one hour followed by treatment with moist CO2 for two hours. The resulting product, which was filtered, contained 17.8 weight percent barium (1.35 mol Ba/mol OH) and the weight percent conversion of hydroxyl was about 135. The product was analyzed for CO2 content by an acid hydrolyses procedure, and it was determined to contain 3.7 weight percent CO2, giving a ratio of 0.64 mol COa/mol hydroxyl in the product.

In another similar run, when using a Ba/OH mol ratio of 2:1 and treating only with moist CO2, the final product contained a mol ratio of l.2::1.0 Ba/OH and 0.45 :1.0 COz/OH (1.43 weight percent CO2).

Examplej TABLE II Barium in final treating time, hours product,

weight percent 1 Equivalent to about 2% by weight 002 based on total reaction mixture or about 0.9 mol 002 per mol 0H radical in the oil solution containing the alkyl phenol sulfide.

Under the conditions used, a C02 treating time of 30 minutes was insutficient to obtain elfective utilization of barium. Treatment with CO2 for a period of over one hour increased the barium utilization only slightly. Above about 1.0 mol COz/mol OH was needed to obtain effective utilization of barium under the conditions used. With more effective contacting apparatus, the short treating time would have given more favorable results.

' Example4 A run was carried out in which tert.-octyl phenol was neutralized with barium hydroxide pentahydrate. The mixture, containing about alkyl phenol, 81% mineral oil and 4% Ci2-C1a alcohols, was treated with the barium hydroxide using a barium to hydroxyl mol ratio of about 4:1. During neutralization, the reacting mixture was treated with steam for one hour followed by blowing with moist CO2 for two hours. The final filtered product contained 22.6 weight percent barium, representing a mol rat-i0 of barium to phenol hydroxyl of about 3.3:1.

ExampleS Reactions were carried out substantially in accordance with the procedure described in Example 1 with the exception that lime was used as a neutralization agent. The mol ratio of calcium to OH radicals was about 2:1. The product prepared without treatment with steam and CO2 during neutralization contained about 2.4 weight percent calcium. The product prepared in which the material was treated with steam and CO2 during neutralization also contained about 2.4 weight percent calcium. Treatment in accordance with the present invention has no substantial effect on total calcium content or conversion when employing lime as a neutralizing agent.

What is claimed is:

1. The process of forming a barium salt of a phenolic compound containing more than one molof barium per mol of hydroxyl radical which comprises the steps of treating a phenolic compound with a substantial excess of a basic barium neutralizing agent while contacting the reacting mixture with gaseous carbon dioxide and water, the mol ratio of barium to phenol hydroxyl radical being above about -l.3:1.0 and the mol ratio of carbon dioxideto phenol hydroxyl radical being above about 0.2:1:0 during the treating step.

2. A process as in claim 1 wherein said reacting mixture is first treated with steam followed by treatment with gaseous CO2 containing steam.

3. A process as in claim 2 wherein said phenolic compound is an alkyl phenol sulfide.

4. A process as in claim 2 wherein said phenolic compound is an alkyl phenol.

5. The process of forming a barium salt of a phenolic compound which comprises treating a compound containing at least one hydroxyl radical attached to an aromatic ring with a basic barium neutralizing agent in the presence of carbon dioxide and water, the molar ratio of barium to hydroxyl radical being above about 1.521 and the molar ratio of carbon dioxide to hydroxyl radical being above about 04: 1 whereby a product containing more than one mol barium per mol of hydroxyl radical is formed.

6. A process as in claim 5 wherein said treatment is carried out at a temperature in the range of about 50 to 200 C.

7. A process as in claim 6 wherein said phenolic compound is dissolved in an inert'solvent during said treatment.

8. A process as in claim 7 wherein said phenolic compound is an alkyl phenol sulfide.

9. A process as in claim 8 wherein said neutralization reagent is a barium hydroxide.

References Cited in the file of this patent UNITED STATES PATENTS 2,406,041 Schneider et a1 Aug. 20, 1946 2,449,026 Gilder et al. Sept. 7, 1948 FOREIGN PATENTS 600,825 Great Britain Apr. 20, 1948 

1. THE PROCESS OF FORMING A BARIUM SALT OF A PHENOLIC COMPOUND CONTAINING MORE THAN ONE MOL OF BARIUM PER MOL OF HYDROXYL RADICAL WHICH COMPRISES THE STEPS OF TREATING A PHENOLIC COMPOUND WITH A SUBSTANTIAL EXCESS OF A BASIC BARIUM NEUTRALIZING AGENT WHILE CONTACTING THE REACTING MIXTURE WITH GASEOUS CARBON DIOXIDE AND WATER, THE MOL RATIO OF BARIUM TO PHENOL HYDROXYL RADICAL BEING ABOVE ABOUT 1.3:1.0 AND TE MOL RATIO OF CARBON DIOXIDE TO PHENOL HYDROXYL RADICAL BEING ABOVE ABOUT 0.2:1:0 DURING THE TREATING STEP. 